Fuel pump with oil seal diaphragm



y 1963 I D. ToscHKbFF 3,381,591

FUEL PUMP WITH OIL SEAL DIAPHRAGM Original Filed Feb. 9. 1966 INVENTOR.

United States Patent 3,381,591 FUEL PUMP WITH OIL SEAL DIAPHRAGM Dimitar Toschkotf, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Continuation of application Ser. No. 526,219, Feb. 9, 1966. This application Apr. 12, 1967, Ser. No. 630,462 8 Claims. (Cl. 92-168) ABSTRACT OF THE DISCLOSURE A fuel pump in which a longitudinally recip'rocable plunger is adapted to actuate a pumping diaphragm through an oil seal protector assembly, the latter including a flexible sealing diaphragm of special hub and peripheral margin construction insuring an effective long life seal against leakage along the plunger and sealing diaphragm hub interface and also around the periphery of the sealing diaphragm.

This application is a continuation of application Ser. No. 526,219, filed Feb. 9, 1966, now abandoned.

State of the prior art An improved oil seal assembly in a fuel pump has been described in the US. patent application Ser. No. 355,803, now Patent No. 3,242,868, filed Mar. 30, 1964 in the name of John Gold. Leakage has now and then occurred in such pumps when subjected to arduous service and for reasons not readily apparent.

Description of the invention In the drawings:

FIGURE 1 is an elevation view of a fuel pump presenting one embodiment of the present invention with portions broken away better to illustrate the construction;

FIGURE 2 is an exploded and enlarged perspective view of a subassem'bly utilized in the pump of FIGURE 1 and a portion of one element being broken away; and

FIGURE 3 is a greatly enlarged sectional view of a portion of the sealing structure incorporated in the pump assembly of FIGURE 1.

The pump of FIGURE 1 is much like that described in the above mentioned patent application Ser. No. 355,803. The supporting body of the pump defines an L-shaped passage 12 giving communication with the crankcase of an internal combustion engine and a camshaft 14 of the engine is adapted to oscillate a rocker arm 16 about a 'pin 18 mounted in the body 10. The rocker arm 16 with the help of a pum'p'ing spring 20 and a smaller upper spring 22 is adapted to reciprocate a pumping diaphragm plunger 24. The lower end of the plunger is fixed with the aid of protective plates 26 and 28 to a pumping diaphragm 30 and the margin of the latter is clamped between the body 10 of the pump and a peripheral flange 312 of the lower ca'sing part 34 of the pump. This latter part 34 includes one-way valves, an inlet and an outlet as is conventional in such pumps.

The body 10 with the help of a flexible sealing diaphragm 36 as well as the pumping diaphragm 30 defines a spring chamber 38 and the latter is vented at 40' to the atmosphere.

The lower end of the spring 20 bears against the upper protector plate 26 of the pumping diaphragm and the upper coil of the spring bears against a frusto-conical rigid member 42 which is interposed between the sealing diaphragm 36 and the spring 20.

The rubbery flexible sealing diaphragm 36 bears a peripheral portion 44 and a hub portion 46. Each of these portions annularly grooved to facilitate sealing of the chamber 38 from the passage 12 leading to the engine. T wo grooves 48 and 50 are formed in the upwardly facing marginal portion of the flexible diaphragm 36 and the groove 48 is partially defined by a lower or horizontal surface 52 upon which is located an annular series of four equally sp'aced projections 54.

The hub 46 is annularly grooved as at 56 so that the annular ridges 58 defining the groove extend around the plunger 24 and, in effect, form two effective seals against leakage at the interface between the hub and the plunger. This hub 46 is made less in axial length than heretofore utilized while employing a plain or ungrooved cylindrical surface for engaging the plunger. The reason for this reduction is that each ridge does a better job in forming a seal than was performed by the single cylindrical surface in prior pumps. It is to be noted in this particular construction that no copper coating is necessary for the plunger in order to make an effective joinder of the hub to the plunger and this entails a considerable cost saving.

In the seal arrangement as shown in FIGURE 2 and 3, it will be noted that the four projections 54 on the diaphragm 3 6 are of such size that they resiliently hold the margin of a rigid protector 60 snugly against a horizontal surface or shoulder 62 of the body 10. The latter has a series of four arcu'ate recesses 64 extending from a surface 66 of the pumping body. The surface accurately pilots a series of projections 68 formed as integral parts of the rigid protector 60. These projections are not essential insofar as the present invention is concerned but it is preferred that they be utilized together with the special provisions on the sealing diaphragm 36 in maintaining the protector 60 in accurate and fixed position relative to the pump body.

An outside rim or edge 70 of the sealing diaphragm 36 snugly engages an inner wall surface 72 of the pump body so that the marginal portion 44 of the diaphragm 36 is aided in playing its part effectively i.e. in keeping the sealing members accurately positioned.

The rigid protector 60 is preferably made of plastic such as nylon and it bears openings 74 which vent an annular space 76 surrounding the plunger 24 and defined by the protector 60 and the sealing diaphragm 36. Grooves 79 are provided in the protector 60 better to engage the body 10 but such grooves are not essential in practicing the invention.

When the pump is operated, the plunger 24 will reciprocate longitudinally and the sealing diaphragm 36 will roll smoothly up and down on the inner surface of the rigid member 42, The space 76 will be vented by the openings 74 and the vents 40 will do the same thing for the spring chamber 38 so there is no fluid pressure interference with the action of the sealing diaphragm, 3 6. Reversal of cur-vature of the later will be prevented'by an annular bulge 80 (FIGURE 1) formed on the protector 60 and facing the diaphragm 36.

Each projection 54 and the rim 70 each constitutes a stop portion which is integral with the sealing diaphragm and serves to retain the latter and the protector in their proper positions.

I claim:

1. A fuel pump comprising a pump body defining a passage and having a shoulder surrounding said passage, pumping means including a plunger longitudinally movable in said passage, a flexible sealing diaphragm having a central portion movable with said plunger, a rigid protector slidable on said plunger, annular bulges on said sealing diaphragm and rigid protector each extending away from said shoulder so that reversal of curvature of said sealing diaphragm during pump operation is prevented, a vent in said rigid protector, spring means urging the peripheries of said rigid protector and sealing diaphragm 3 toward said shoulder to form an annular seal, and at least one surface on said pump body facing the axis of said plunger and contacting said rigid protector to prevent lateral displacement of the latter and said sealing diaphragm with respect to said pump body.

2. A .fuel pump as set forth in claim 1, an annular series of tabs integral with said rigid protector and engaging said one surface on said pump body.

3. A fuel pump as set forth in claim 2, said one surface on said pump body being a continuous annular surface, said rigid protector being of plastic material with said tabs snugly fitting within said continuous annular surface.

4. A fuel pump comprising a pump body defining a passage and having a shoulder surrounding said passage, pumping means including a plunger with the latter longitudinally movable in said passage, a flexible sealing diaphragm having a peripheral portion and a hub portion, said peripheral and hub portions being grooved to impart a sealing effect, a rigid protector slidable on said plunger, a bulge in said protector extending toward said sealing diaphragm and adapted to prevent sealing diaphragm curvature reversal, spring means urging said peripheral portion toward said shoulder and said protector, stop portions integral with said sealing diaphragm and interposed between and contacting said pump body and said rigid protector, and the arrangement being such that said stop portions cooperate with said spring means to retain said sealing diaphragm and rigid protector in a predetermined position with relation to said ump body.

5. A fuel pump as set forth in claim 4, the said grooved hub portion being such that ridges thereof defining the sides of at least one groove snugly engage and surround the said plunger to constitute a seal.

6. A .fuel pump as set forth in claim 4, the said rigid protector having a vent therein and having its axial position in said pump body determined by an annular portion of said sealing diaphragm snugly interposed between the periphery of said protector and an inner wall surface of said pump body.

7. A fuel pump as set forth in claim 4, a frusto-conical rigid member being interposed between said spring means and said peripheral portion of said sealing diaphragm to serve as a surface upon which said sealing diaphragm is adapted to roll, an annular space defined between said plunger and said rigid protector, and the latter having an opening adapted to serve as a vent for said space.

8. A fuel pump as set forth in claim 4, the grooves of said peripheral and hub portions extending around said plunger, and said stop portions including an annular series of spaced projections resiliently engaging said rigid protector and adapted to prevent rotation of the latter with respect to said pump body.

References Cited UNITED STATES PATENTS 2,285,215 6/1942 Lotz 230-170 2,634,687 4/1953 Smith 74-182 2,873,688 2/1959 Elder 10315O 3,135,218 6/1964 Toschkoff 103-150 3,242,868 3/1966 Gold 10315O DONLEY J. STOCKING, Primary Examiner.

WILLIAM L. FREEH, Examiner. 

